IMPACT OF COGNITIVE BIAS MODIFICATION TRAINING ON P100 IN DEPRESSION AND HEALTHY CONTROLS

Major depressive disorder (MDD) is characterized by alterations in emotion processing, including reduced responsiveness to positive stimuli and increased sensitivity to negative information. While prior research has primarily focused on explicit emotion regulation strategies, early cortical mechanisms of emotional processing remain insufficiently understood. The P100 event-related potential (ERP) component provides a valuable marker of early visual–emotional processing. We examined 100 patients with MDD and 101 healthy control subjects using 64-channel EEG recordings before and after a randomized controlled cognitive bias modification (CBM) intervention (Positive vs. Control Training) implemented via a dot-probe task. P100 amplitudes and latencies were analyzed at left and right hemispheric electrodes in response to emotional stimuli varying in valence (positive/negative), arousal (low/high), and target status (target/non-target). CBM did not significantly affect P100 amplitudes or latencies in MDD patients and showed only limited, condition-specific effects in HCS. Across groups, P100 amplitudes decreased from pre- to post-assessment, particularly in women, were larger for target than non-target stimuli, and exhibited right-hemispheric dominance. Emotional valence and arousal further modulated P100 responses, whereas clinical variables including depression severity, anxiety, trauma history, and medication status had no significant influence. Overall, the P100 component in MDD appears insensitive to CBM training and symptom change, while remaining sensitive to emotional valence and arousal irrespective of diagnostic status, suggesting that CBM-related changes in emotional processing may emerge at later stages of information processing rather than during early perceptual encoding.